Associated with gas turbines having multiple cannular combustors are transition ducts defining fluid passages that carry hot gases from the combustors to the turbine inlet. Typically, the combustors are round, but the turbine inlet is annular. Each transition duct directs the hot gases to a section of the annular turbine inlet. Therefore, the transition duct bodies have round inlets and an exit that forms a segment of an annulus, which may substantially be close to a rectangular shape.
A current design of a transition duct is manufactured via two opposing skins which are pressed into the basic shape and then hand worked. Butt welded joints are applied for the final mating. This is typically a manual and slow process which needs precision hand working. Besides, the used material is stiff and therefore difficult to handle during manufacturing.
U.S. Pat. No. 7,047,615 B2 discloses a method of hydroforming one or more transition duct bodies between two dies in a hydroforming press. This may allow to produce transition duct bodies with no longitudinal welds.